1. Field of the Invention
The present invention relates to a specific siloxane mixture wherein the siloxanes carry aminoalkyl and alkoxy groups and, where appropriate, alkyl groups and also where appropriate, hydroxyl groups and the mixture is obtainable by a particular process. The present invention further relates to the use of such mixtures and to compositions, i.e., formulations, coatings, articles, etc., which are based on the inventive mixture.
2. Description of the Background
Organofunctional silanes and also siloxanes are used, inter alia, to modify the properties of surfaces or as a reactive component in formulations, especially in coating compositions or in compounds.
Mixtures of linear and cyclic siloxane oligomers may be obtained by controlled hydrolysis and/or condensation of organofunctional alkoxysilanes. One particular problem associated with the preparation of polyfunctional siloxane oligomers is the extremely different hydrolysis and/or condensation behavior of the individual organoalkoxysilanes and organochlorosilanes. The activity of differently composed or differently prepared siloxane mixtures is also generally different.
EP 0 716 128 A2, EP 0 716 127 A2, and EP 0 675 128 A1 disclose aqueous solutions of amino-functional and OH-containing organosilanes and organosiloxanes. These organosilane systems are almost completely hydrolyzed and the organofunctional silicon units are in random distribution in the cocondensates.
EP 0 518 057 A1 and DE 196 24 032 A1 disclose mixtures of linear and cyclic vinyl-functional and also alkyl-functional siloxane oligomers which also carry alkoxy groups. Such mixtures are used, for example, to hydrophobicize mineral surfaces and pulverulent surfaces and also as crosslinking agents for thermoplastic polyolefins.
DE 198 34 990 discloses mixtures of linear and cyclic siloxane oligomers containing acryloyloxypropyl or methacryloyloxypropyl groups. Such siloxane oligomer mixtures may be used, for example, to treat mineral surfaces or the surfaces of pulverulent substances, such as titanium dioxide, talc, clay, silicas, quartz, kaolin, aluminum hydroxide, magnesium hydroxide, bentonite, montmorillonite, mica (muscovite mica), and calcium carbonate (chalk, dolomite). Said siloxane oligomer mixtures are also used as adhesion promoters in rubber compounds filled, for example, with kaolin.
EP 0 997 469 A2 discloses mixtures of linear and cyclic siloxane oligomers which carry aminopropyl, alkoxy, and, if desired, alkyl groups, the organofunctional silicon units in these cocondensates also being in random distribution.
It is an object of the present invention to provide additional organofunctional siloxane mixtures based on amino-functional Si compounds.
It has surprisingly been found that a novel mixture of aminoalkyl-, alkoxy-, where appropriate alkyl-, and, where appropriate, hydroxy-functional siloxanes can be prepared by subjecting (i) at least one tetraalkoxysilane or (ii) at least one hydrocarbon-alkoxysilane or (iii) a mixture of at least one tetraalkoxysilane and at least one hydrocarbon-alkoxysilane to partial hydrolysis and precondensation by addition of water and acid, thereafter adding at least one aminoalkyl-functional alkoxysilane to the resulting siloxane reaction mixture, with aminoalkylsilanes being condensed onto the siloxane units present in the reaction mixture and substantially enveloping them so that the aminoalkyl groups are oriented outward, and subsequently removing the alcohol from the system. In this way it is possible in an advantageous way to provide a novel amino-functional siloxane mixture.
Thus, the present invention provides a mixture of aminoalkyl-, alkoxy-, and, optionally, alkyl-, and, optionally, hydroxy-functional siloxanes, obtainable by a process comprising subjecting (i) at least one tetraalkoxysilane or (ii) at least one hydrocarbon-alkoxysilane or (iii) a mixture of at least one tetraalkoxysilane and at least one hydrocarbon-alkoxysilane to controlled hydrolysis and precondensation by addition of water and acid to produce a siloxane reaction mixture, followed by adding at least one aminoalkyl-functional alkoxysilane to the siloxane reaction mixture, and removing alcohol from the reaction mixture.
The present invention also provides a process for preparing a siloxane mixture described above, comprising subjecting (i) at least one tetraalkoxysilane or (ii) at least one alkylalkoxysilane or (iii) a mixture of at least one tetraalkoxysilane and at least one alkylalkoxysilane to controlled hydrolysis and precondensation by addition of water and acid, thereafter adding at least one aminoalkyl-functional alkoxysilane to the resulting siloxane reaction mixture, and removing alcohol from the reaction mixture.
The present invention additionally provides an organic resin composition, comprising an organic resin and the siloxane mixture described above.
In addition, the present invention provides a method of making the resin composition described above, comprising incorporating the siloxane mixture described above into the organic resin.
The present invention also provides a paint composition, comprising a paint and the siloxane mixture as described above.
In another embodiment, the present invention provides a method of making the paint composition described above, comprising incorporating the siloxane mixture described above into the paint.
The present invention also provides a varnish composition, comprising a varnish and the siloxane mixture described above.
The present invention additionally provides a method of making the varnish composition described above, comprising incorporating the siloxane mixture described above into the varnish.
The present invention also provides a method of treating a mineral, organic, or metallic surface, comprising applying the siloxane mixture described above to the surface.
In another embodiment, the present invention also provides a method of hydrophobicizing a surface, comprising applying the siloxane mixture described above to the surface.
The present invention also provides a method of surface-modifying a pulverulent substance, comprising treating the substance with the siloxane mixture described above.
Further, the present invention also provides a method of silanizing fillers and pigments, comprising treating a filler or a pigment with the siloxane mixture described above.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the detailed description below.